SA front drum brake conversion

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Phileas
Posts: 226
Joined: 18 Feb 2009, 6:12pm
Location: Bristol

Re: SA front drum brake conversion

Postby Phileas » 4 Jan 2020, 11:52am

cycle tramp wrote:Happy New Year! Have you fitted the brake, yet? And if have can I ask how you found it, and do you have any photos?

A happy new year to you too.

There’s a delay in fitting as I have to swap forks which requires a reducer bush (which I’ve got) to allow fitting a straight steerer in a tapered head tube and a visit to my LBS to fit said bush to the fork. So it won’t be done this weekend unfortunately.

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SimonCelsa
Posts: 633
Joined: 6 Apr 2011, 10:19pm

Re: SA front drum brake conversion

Postby SimonCelsa » 4 Jan 2020, 5:03pm

Thanks for all the previous info regarding fitting the SA front hub brake. Hopefully this will see me good for a smooth transition into drum brake fitting and operation. I've still to buy all the parts and build the wheel but hopefully should be in operation before the end of the month.

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speedsixdave
Posts: 688
Joined: 19 Apr 2007, 1:48pm
Location: Nottingham, UK

Re: SA front drum brake conversion

Postby speedsixdave » 4 Jan 2020, 6:11pm

Brucey wrote:
speedsixdave wrote:
Brucey wrote:In particular the height of the reaction arm clip for the front brake makes a big difference to how easy it is to refit the wheel. Also the reaction arms need to be 'set' so that they are not being strained sideways when the wheel is installed; if not then the wheel is less easy to refit and the brakes won't work as consistently well as they should.


...Does 'set' mean 'bent', Brucey?....


that's about the size of it

…. And can you expand on the correct height of the reaction arm clip?.....


In the simplest terms it needs to be set as low as it can be. With the wheel in, and the brake arm 'set' to the correct lateral alignment, you should slide the clip down as far as it will go. There is a ~10mm wide 'tang' on the end of the brake arm which is about an inch long. If this always enters the reaction arm clip before you need to worry about the axle going into the dropouts, it makes for easier refitting of the wheel, every time. When the clip is set correctly the top half of the tang will be visible above the clip.

FWIW you can buy reaction arm clips in various different sizes; IIRC the one that comes with a new hub will fit most traditional profile forks with a 1" steerer. You will need a different clip for many other forks, and occasionally something will have to be made/adapted to suit.

cheers


Thanks Brucey, very helpful as always.
Big wheels good, small wheels better.
Two saddles best!

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: SA front drum brake conversion

Postby Brucey » 5 Jan 2020, 1:24pm

rear reaction arm clips are listed here

http://www.sturmey-archer.com/en/products/rear-brake-arm-clips

and front reaction arm clips are here

http://www.sturmey-archer.com/en/products/front-brake-arm-clips

there are four different diameters and two patterns (not in all sizes, but single or double bolt) of rear clip. Sizes include 15.5mm, 15.9mm, 17.0mm. 19.1mm, 22.2mm.

Front reaction arm clips are different and currently there are two sizes; 22.2mm (7/8", HSL703) and 17.5mm (11/16", HSL702). IIRC you normally get the smaller one with a front brake hub when you buy it. A clip that is slightly too large can be packed out (e.g. with the rubber strip supplied, or with something thicker) so that clip will fit a smaller dimeter fork blade if required.

IME the rubber strip supplied is not made from very weather resistant rubber (about as likely to perish as a strip cut from an old inner tube). The clips are made of plated steel and can corrode. IME this happens most quickly at the rear because of salt spray off the front wheel. The front clip sees less spray so usually lasts longer.

These clips are available from stockists such as SJS or Practical Cycles.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

cycle tramp
Posts: 609
Joined: 5 Aug 2009, 7:22pm

Re: SA front drum brake conversion

Postby cycle tramp » 9 Jan 2020, 7:37pm

Brucey wrote:rear reaction arm clips are listed here

http://www.sturmey-archer.com/en/products/rear-brake-arm-clips

The clips are made of plated steel and can corrode. IME this happens most quickly at the rear because of salt spray off the front wheel. The front clip sees less spray so usually lasts longer.

cheers


Apologies for the thread drift, but could one not avoid corrosion of the rear clip by affixing it to the seat stay rather than the chain stay? That way the cable could be routed along the top tube and down the seat stay...

Brucey
Posts: 36644
Joined: 4 Jan 2012, 6:25pm

Re: SA front drum brake conversion

Postby Brucey » 9 Jan 2020, 7:57pm

the seat stays on most traditional steel frames are probably not strong enough to accept a reaction arm load; for whatever reason the reaction arm is shorter on rear brakes than fronts, so the loading is higher, for any given torque on the brake (which will usually be lower for a rear brake admittedly). There is also a potential issue with positioning the brake arm when the wheel is being fitted and removed; normally the brake arm hangs down and can (unless there is an IGH in use) be simply rotated into position once the wheel is in. However the brake arm probably can't be swung past the chainstay in every case, so it might be difficult to get it in correct position next to the seatstay, if a seat stay clamp is used.

A seatstay mount would also encourage the brake cable to be routed along the top tube and down the seat stay; this might be preferable in some cases.

One thing I do think is that there is almost always room for improvement in the setup, vs what you get if you just use the parts in the obvious way.

For example the usual method on the rear brake arm is to use a bolt, nylock nut and at least one, usually two washers. This is a bit fiddly when refitting the wheel and needs two tools to release the arm. A single screw into a captive fitting would be quicker/simpler (with fewer parts to drop and lose), but would need some secondary retention (eg an 'R' clip) to ensure that the bolt doesn't drop out.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Phileas
Posts: 226
Joined: 18 Feb 2009, 6:12pm
Location: Bristol

Re: SA front drum brake conversion

Postby Phileas » 24 Jan 2020, 3:20pm

Just for completeness. I finally fitted the brake. I’ve used it for three commutes so far. It’s ok - I assume it will significantly improve as the pads wear-in.

(I realise the fork looks a bit ugly in this frame.)
F81A4F8E-8165-41E0-8212-2E166CF3B7E1.jpeg
Image Attachments
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David
Posts: 130
Joined: 11 Jan 2007, 5:13pm

Re: SA front drum brake conversion

Postby David » 24 Jan 2020, 3:55pm

I did this several years ago.

I wouldn't do it again.

I found the front shoes wore quickly - they didn't last as long as a good set of pads.

I had to strip the whole thing down after one winter because the cam siezed and the brakes wouldn't release.

After a certain wear point, the front brake would "servo" on and I would have to rock the bike backwards to free the shoes. Worse still, it would snatch and lock the front wheel solid just before coming to a gentle stop and I'd have to do an emergency unclip - I normally try to ride smoothly, am light on the brakes and try to avoid dabbing my feet down (I love track stands 8) ) so having the brakes lock on was a big headache for me.

The brakes didn't improve much with age. They were adequate but still outperformed by a good set of pads.

The rear brake was always gentle, it would lock the rear wheel if lightly loaded but with heavy panniers it was incapable of locking the wheel.

I tried different advantage levers to see if it would improve but no real joy.

I did like the five speed hub and the dynamo but they were both let down by the brakes.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: SA front drum brake conversion

Postby Brucey » 24 Jan 2020, 4:51pm

FWIW if you don't have a little lube on the cam then the brakes can fail to release fully. Other than that the experience related above I'd describe as 'atypical'. A high wear rate suggests that the brake were dragging all the time or that the brake shoes were contaminated somehow; they will certainly wear quickly if the shoes are contaminated with oil.

Remember that these brakes were designed to meet a requirement that the shoes should last five years of daily use by a postman. There are not many uses which are more strenuous than that, but there are various things which might cause the brakes to perform less well than anticipated.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

cycle tramp
Posts: 609
Joined: 5 Aug 2009, 7:22pm

Re: SA front drum brake conversion

Postby cycle tramp » 24 Jan 2020, 11:13pm

David wrote:I did this several years ago.

I wouldn't do it again.

I found the front shoes wore quickly - they didn't last as long as a good set of pads.

I had to strip the whole thing down after one winter because the cam siezed and the brakes wouldn't release.

After a certain wear point, the front brake would "servo" on and I would have to rock the bike backwards to free the shoes. Worse still, it would snatch and lock the front wheel solid just before coming to a gentle stop and I'd have to do an emergency unclip - I normally try to ride smoothly, am light on the brakes and try to avoid dabbing my feet down (I love track stands 8) ) so having the brakes lock on was a big headache for me.

The brakes didn't improve much with age. They were adequate but still outperformed by a good set of pads.

The rear brake was always gentle, it would lock the rear wheel if lightly loaded but with heavy panniers it was incapable of locking the wheel.

I tried different advantage levers to see if it would improve but no real joy.

I did like the five speed hub and the dynamo but they were both let down by the brakes.


I have to say that this hasn't been my experience. I've been using them for 3 and a bit years, the drum brakes have got stronger, and there's been very little wear - indeed I've only had to tension the brake wires once ir twice to take up the stretch... even better during that time I've suffered no wear to my wheel rims.

cycle tramp
Posts: 609
Joined: 5 Aug 2009, 7:22pm

Re: SA front drum brake conversion

Postby cycle tramp » 24 Jan 2020, 11:15pm

Phileas wrote:Just for completeness. I finally fitted the brake. I’ve used it for three commutes so far. It’s ok - I assume it will significantly improve as the pads wear-in.

(I realise the fork looks a bit ugly in this frame.)
F81A4F8E-8165-41E0-8212-2E166CF3B7E1.jpeg


That looks good - the brake performance will get better. Looking forward to hearing an update in a few months time :-)

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SimonCelsa
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Re: SA front drum brake conversion

Postby SimonCelsa » 25 Jan 2020, 5:44am

What's the item encircled in red?

It looks like an in-line barrel adjuster, is it to facilitate removal of the front brake cable.

Hub brake.jpeg
Hub brake.jpeg (34.52 KiB) Viewed 169 times


Cheers, Simon

Phileas
Posts: 226
Joined: 18 Feb 2009, 6:12pm
Location: Bristol

Re: SA front drum brake conversion

Postby Phileas » 25 Jan 2020, 9:00am

SimonCelsa wrote:What's the item encircled in red?

It looks like an in-line barrel adjuster, is it to facilitate removal of the front brake cable.


Cheers, Simon


Actually, it was part of the disc brake set-up and I decided to leave it there for the moment because I couldn’t be bothered to use a single piece of outer which would have entailed redoing the bar tape. :oops:

It doesn’t even work anymore, it’s seized up.

Of course, I’ve just realised I should have replaced the lever with a short pull type. That explains the slightly disappointing braking performance. ( :oops: again)

Phileas
Posts: 226
Joined: 18 Feb 2009, 6:12pm
Location: Bristol

Re: SA front drum brake conversion

Postby Phileas » 25 Jan 2020, 1:40pm

Now I’m confused.

I assumed my brake levers were the wrong type because they came from a Genesis Day One Disc which had TRP Spyre callipers.

However, I found a spec sheet for this bike on Evans cycles https://www.evanscycles.com/genesis-day-one-disc-2015-singlespeed-bike-EV223056 which suggests it had Tektro RL340s which I thought were wrong for disc callipers!

David
Posts: 130
Joined: 11 Jan 2007, 5:13pm

Re: SA front drum brake conversion

Postby David » 25 Jan 2020, 3:32pm

Brucey wrote:FWIW if you don't have a little lube on the cam then the brakes can fail to release fully. Other than that the experience related above I'd describe as 'atypical'. A high wear rate suggests that the brake were dragging all the time or that the brake shoes were contaminated somehow; they will certainly wear quickly if the shoes are contaminated with oil.

Remember that these brakes were designed to meet a requirement that the shoes should last five years of daily use by a postman. There are not many uses which are more strenuous than that, but there are various things which might cause the brakes to perform less well than anticipated.

cheers


No, it was all clean & definitely not dragging. I was surprised at how quickly the brakes went off and needed replacing. I was also surprised at how little wear there was on the shoes when I replaced them. I also got almost no dust out. It was only the front brake I had problems with, the back brake - apart from being a bit weak was fine from a serviceable perspective.

I replaced the front shoes about 18 months because of them jamming on. The new shoes didn't make a big improvement and TBH I couldn't see a big difference in the thickness of the linings. The new shoes lasted about 6 months before they started snatching on and I decided to call it a day with them.

I think you are probably right about this being atypical - I went the drum brake route because I was pretty sure the PO Pashleys wouldn't use them if they were useless. I was expecting 5 years trouble free life from them but the front brake just wouldn't play. Maybe the Posties don't use them in winter on salted roads :D

I eventually scrapped the bike and built a new one but fitted disc brakes - these work fine but I did contaminate the pads and junked them after about 200 miles, the replacement ones have been good for over 1500 miles so far.